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BV022061 10:07AM | 04/05/20

I changed out an old light fixture. It had 3 blacks, 3 whites and 1 red. Hooked up the lines but the light switch would not work. Found out red wire is the switch so connected black to red. Switch and light working now. Problem is when I mount the fixture to the bracket the tighter I make screws just before it is flush with the ceiling the light goes out and circuit trips. There is foil on the backside of the light. Could that be shorting it out when it meets the bracket?

thanks, Robert Vega

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  • Check all your connections and make sure you're not pinching a wire when screwing in the fixture.
    – JACK
    Apr 5 '20 at 14:52
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    When you tighten the screws you are probably running into a wire and cutting into it's insulation. Is the fixture on a circuit protected by an AFCI breaker? If not and it's an over-current trip, the foil would be severely damaged by a short, so it's probably a screw piercing a wire. Pull it all out (WITH THE POWER OFF) and carefully check the insulation. Then carefully press the wires into the box, paying attention to where the screws go. If they are overly long, it might work to get shorter screws. Apr 5 '20 at 15:00
  • Thanks for the info George. Let me try your suggestions. Apr 5 '20 at 15:06
  • Please let us know what you find. Here at SE, often times the problem got solved and we don't know it or what solution worked. When you post the solution, others can see it and learn from you! Apr 5 '20 at 15:10
  • You nailed it @George; you should make that an answer. Apr 5 '20 at 16:34
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For folks reading this in the future: I have also found that, with 3 or more wires, sometimes the wire-nut does not screw on all the way, leaving some of the bare wire exposed. May not always be easy to see. Then, when tightening the cover, it shorts out. $0.02

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I'm going to answer this based on a comment earlier, at Harp's suggestion after hearing back from the OP.

When you tighten the screws you are probably running into a wire and cutting into it's insulation. Is the fixture on a circuit protected by an AFCI breaker? If not and it's an over-current trip, the foil would be severely damaged by a short, so it's probably a screw piercing a wire. Pull it all out (WITH THE POWER OFF) and carefully check the insulation. Then carefully press the wires into the box, paying attention to where the screws go. If they are overly long, it might work to get shorter screws.

The OP's most recent comment states that wires were coming apart as he tighten the fixture screws. Because it tripped a breaker, I'm assuming the hot contacted a ground, or neutral. He fixed it via larger wire nuts.

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